Hydraulic cylinder, for example for use with a hydraulic tool

Abstract

The invention relates to a hydraulic cylinder, for example for use with a hydraulic tool, which hydraulic tool is provided with a frame and an element which is movable with respect to the frame by means of the hydraulic cylinder.A hydraulic tool which is operated by means of a hydraulic cylinder as described above is known from, for example, European patent no. 0641618. This patent discloses a frame which is coupleable to a jib of an excavator or the like and to which an assembly of two jaws can be coupled. One of the jaws is pivotable with respect to the other jaw by means of a hydraulic adjusting cylinder (a double-acting piston/cylinder combination).

The invention claimed is: 
     
       1. A hydraulic cylinder, for use with a hydraulic tool, which hydraulic tool is provided with a frame and an element which is movable with respect to the frame by means of the hydraulic cylinder, wherein the hydraulic cylinder comprises:
 a supply for a pressurized fluid; 
 one piston/cylinder combination comprising 
 a cylinder body provided with a first, closed end and a second, open end and 
 a piston body accommodated in the cylinder body, provided with a piston rod extending from the second, open end of the cylinder body, wherein 
 the cylinder body and the piston body delimit a first cylinder chamber and the cylinder body, the piston body and the piston rod delimit a second cylinder chamber, wherein 
 the piston rod is hollow and is in fluid communication with the second cylinder chamber near the piston body, and 
 the cylinder body comprises a cylinder rod which extends through the piston body from the first end and into the hollow piston rod and is provided with a cylinder piston body, wherein 
 the cylinder piston body and the hollow piston rod delimit a third cylinder chamber, and wherein 
 in use, the piston body and the cylinder piston body perform alternately outward and inward working cycles on account of pressurized fluid supplied to the first, second and third cylinder chamber, respectively, via a first fluid line, second fluid line, and third fluid line, respectively, as well as 
 at least a first control valve accommodated in a first valve block, which first control valve has two clack valves for controlling the supply of pressurized fluid via the first fluid line and second fluid line to the first cylinder chamber and second cylinder chamber respectively, as well as at least one second control valve which is accommodated in a second valve block, which at least one second control valve controls the supply of pressurized fluid to the third cylinder chamber via the third fluid line, and wherein the first control valve further comprises a pilot pressure valve which controls the opening of the clack valve in the first fluid line, based on a fluid pressure in the second fluid line. 
 
     
     
       2. The hydraulic cylinder according to  claim 1 , wherein the first valve block is fitted against and near the open end of the cylinder body. 
     
     
       3. The hydraulic cylinder according to  claim 2 , wherein the first fluid line from the first valve block is fitted next to the cylinder body and is connected to the first cylinder chamber near the closed end of the cylinder body. 
     
     
       4. The hydraulic cylinder according to  claim 2 , wherein the second fluid line is partly arranged in the first valve block and is connected to the second cylinder chamber near the open end of the cylinder body. 
     
     
       5. The hydraulic cylinder according to  claim 2 , wherein the second valve block is fitted against the frame. 
     
     
       6. The hydraulic cylinder according to  claim 2 , wherein the third fluid line from the second valve block is connected to the third cylinder chamber via the piston rod extending from the open end of the cylinder body. 
     
     
       7. The hydraulic cylinder according to  claim 1 , wherein the first valve block is connected to the fluid supply by means of rotating fluid couplings. 
     
     
       8. The hydraulic cylinder according to  claim 1 , wherein the closed end of the cylinder body is coupleable to the movable element of the hydraulic tool and the piston rod extending from the open end of the cylinder body is coupleable to the frame of said hydraulic tool. 
     
     
       9. The hydraulic cylinder according to  claim 1 , wherein the cylinder rod is provided with a first bore, which first bore is in fluid communication with the second cylinder chamber from the closed end of the cylinder body to near the cylinder piston body. 
     
     
       10. The hydraulic cylinder according to  claim 9 , wherein the cylinder rod is provided with a second bore, which second bore is in fluid communication with the third cylinder chamber from the closed end of the cylinder body and through the cylinder piston body. 
     
     
       11. The hydraulic cylinder according to  claim 9 , wherein the second valve block is fitted against the closed end of the cylinder body. 
     
     
       12. The hydraulic cylinder according to  claim 11 , wherein the first fluid line, second fluid line, and third fluid line, respectively, are partly arranged in the second valve block and connected to the first cylinder chamber, the first bore, and the second bore, respectively. 
     
     
       13. The hydraulic cylinder according to  claim 9 , wherein the closed end of the cylinder body is coupleable to the frame of the hydraulic tool and the piston rod extending from the open end of the cylinder body is coupleable to the movable element of the hydraulic tool. 
     
     
       14. The hydraulic cylinder according to  claim 9 , wherein the cylinder body is provided with a protective sleeve. 
     
     
       15. The hydraulic cylinder according to  claim 1 , wherein the pilot pressure valve is a pilot pressure valve with atmospheric relief. 
     
     
       16. The hydraulic cylinder according to  claim 1 , wherein the pilot pressure valve cooperates with a pilot-operated non-return valve.